Calibration of the response reduction factors used in Ecuador for steel SMRF

Current procedures of analysis and seismic design of structures are conducted considering elastic behavior. This consideration is possible assuming that the seismic forces are lower than the corresponding ones obtained from the elastic design spectrum prescribed by the seismic code. These forces are computed Response Reduction Factors, which are determined according the structural type, member's constituent materials and the expected ductility of the whole structure, among others. Recently, a strong earthquake strike Ecuador. A large number of buildings collapsed under the action of the ground motion, thereby revealing some weakness in the construction process. This article presents the results of a study on the calibration of the Response Reduction Factors used for special moment resisting framed steel buildings, prescribed by the current Ecuadorian Construction Code. To this end, a set of regular buildings located in a high seismic hazard level zone, has been modelled and analyzed using pseudo-static non-linear procedure. Results were processed according two different methodologies, revealing that the code values prescribed for the Response Reduction Factor overestimate the seismic response of designed buildings, so they should be modified in order to guarantee the seismic safety of new buildings.